Two important groups of animals dominated the Permian landscape: Synapsids and Sauropsids. Synapsids had skulls with a single temporal opening and are thought to be the lineage that eventually led to mammals. Sauropsids had two skull openings and were the ancestors of the reptiles, including dinosaurs and birds.
In the early Permian, it appeared that the Synapsids were to be the dominant group of land animals. The group was highly diversified. The earliest, most primitive Synapsids were the Pelycosaurs, which included an apex predator, a genus known as Dimetrodon. This animal had a lizard-like body and a large bony “sail” fin on its back that was probably used for thermoregulation. Despite its lizard-like appearance, recent discoveries have concluded that Dimetrodon skulls, jaws and teeth are closer to mammal skulls than to reptiles. Another genus of Synapsids, Lystrosaurus, was a small herbivore — about 3 feet long (almost 1 meter) — that looked something like a cross between a lizard and a hippopotamus. It had a flat face with two tusks and the typical reptilian stance with legs angled away from the body.
In the late Permian, Pelycosaurs were succeeded by a new lineage known as Therapsids. These animals were much closer to mammals. Their legs were under their bodies, giving them the more upright stance typical of quadruped mammals. They had more powerful jaws and more tooth differentiation. Fossil skulls show evidence of whiskers, which indicates that some species had fur and were endothermic. The Cynodont (“dog-toothed”) group included species that hunted in organized packs. Cynodonts are considered to be the ancestors of all modern mammals.
At the end of the Permian, the largest Synapsids became extinct, leaving many ecological niches open. The second group of land animals, the Sauropsid group, weathered the Permian Extinction more successfully and rapidly diversified to fill them. The Sauropsid lineage gave rise to the dinosaurs that would dominate the Mesozoic Era.
In the early Permian, it appeared that the Synapsids were to be the dominant group of land animals. The group was highly diversified. The earliest, most primitive Synapsids were the Pelycosaurs, which included an apex predator, a genus known as Dimetrodon. This animal had a lizard-like body and a large bony “sail” fin on its back that was probably used for thermoregulation. Despite its lizard-like appearance, recent discoveries have concluded that Dimetrodon skulls, jaws and teeth are closer to mammal skulls than to reptiles. Another genus of Synapsids, Lystrosaurus, was a small herbivore — about 3 feet long (almost 1 meter) — that looked something like a cross between a lizard and a hippopotamus. It had a flat face with two tusks and the typical reptilian stance with legs angled away from the body.
In the late Permian, Pelycosaurs were succeeded by a new lineage known as Therapsids. These animals were much closer to mammals. Their legs were under their bodies, giving them the more upright stance typical of quadruped mammals. They had more powerful jaws and more tooth differentiation. Fossil skulls show evidence of whiskers, which indicates that some species had fur and were endothermic. The Cynodont (“dog-toothed”) group included species that hunted in organized packs. Cynodonts are considered to be the ancestors of all modern mammals.
At the end of the Permian, the largest Synapsids became extinct, leaving many ecological niches open. The second group of land animals, the Sauropsid group, weathered the Permian Extinction more successfully and rapidly diversified to fill them. The Sauropsid lineage gave rise to the dinosaurs that would dominate the Mesozoic Era.
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